1. Field of the Invention
This invention relates to a circulating vibratory linear parts-feeder and more particularly to a circulating vibratory linear parts-feeder which includes a main trough for transporting parts in one direction; and a return trough for transporting the parts in the opposite direction to the one direction, arranged closely to the main trough, spacing by a small gap from the main trough, and in which the parts are transferred from the downstream end of the return trough into the upstream end of the main trough. The parts are orientated in the main trough by orientating means are discharged from a discharge end to the outside and the other parts are returned from the downstream end of the main trough into the upstream end of the return trough. Thus the parts are being circulated through the main trough and return trough.
2. Description of the Prior Art
A vibratory parts-feeder of the bowl type is well known for supplying parts. A bowl is vibrated in a twisting motion. A linear parts-feeder is connected to the discharge end of the vibratory parts-feeder. The vibratory parts-feeder is highly expensive. The vibration modes of the vibratory parts-feeder and linear parts-feeder are different from each others at the connecting portion of the vibratory parts-feeder and linear parts-feeder. It is troublesome to combine the vibratory parts-feeder with the linear parts-feeder.
A linear parts-feeder is less expensive in which two linear troughs are arranged facing to each other and spaced with a little gap from each other. Parts are transported in opposite directions in the two troughs.
A circulating vibratory linear parts-feeder as shown in FIG. 1 and 2 is disclosed in the Japanese Patent Opening Gazette No. 175724/1998. The circulating vibratory linear parts-feeder 300 includes a main linear feeder 310 with a main trough 321 and a return linear feeder 350 with a return trough 361. A groove 323 for orientating is formed in the main trough 310. The parts are transported in the direction as shown by the arrow u, in the main trough 321, and in the direction as shown by the arrow v, in the return trough 361. A drive part 311 vibrates linearly the main trough 321. Another drive part 351 vibrates linearly the return trough 361. The main linear parts-feeder 310 and the return linear parts-feeder 350 are arranged on a common base.
Sidewalls 324 and 364 are integrally formed with transport surfaces 322 and 362. A guide 327 is made at the downstream end of the transport surface 322. The parts removed from the groove 323 are led to the return trough 361 by the guide 327. The parts transferred from the main trough 321 are transported in the return trough 361, along the arrow v. They are transferred from the downstream end of the return trough into the upstream end of the main trough. The parts led into the groove 323 are supplied to the next stage. The parts removed from the groove are circulated between the main trough and the return trough.
Japanese patent No. 1504417 of this patent assignee discloses a circulating vibratory linear parts-feeder wherein parts are transported in the opposite directions, in the first and second troughs. An orientating track and a lower track are formed in the second trough. The orientated parts are supplied from the orientating track to the outside. An upper track and a lower track are formed in the first trough, in parallel with each other. The first and second troughs are driven by the electromagnets which are connected to a common alternating current source. The amplitudes of the first and second troughs are independently controlled. The parts transported on the lower track of the first trough are led into the lower track of the second trough. The parts transported on the upper track of the first trough are led into the orientating track of the second trough. The parts rejected from the orientating track are fallen down on the lower track. The parts transported on the lower track are led into the upstream end of the first trough, and then distributed to the upper and lower tracks.
Generally, the natural frequencies of the main linear feeder and return linear feeder are so designed as to be near the drive frequency of the drive, so that the main and return troughs are effectively vibrated without interference from the vibration technique. However, the vibrations of the main and return troughs are apt to interfere with each other, and be unstable. Since they are vibrated near the resonant frequencies. The reason seems to be that the vibration of the main trough and return trough are transmitted through the leaf springs and the vibrating-absorbing systems to the mated return trough and main trough. If the amplitudes of the main trough and return trough are equal to each other and opposite in phase, the transmitting force is nearly equal to zero, since they are cancelled from each other. However, they are normally different from each other and so the difference is transmitted to the one trough from the other trough. Generally, a vibration system is unstable at its resonant frequency. Further, parts are apt to jam in the orientating groove, when the trough or the troughs contain too many parts.
It is an object of this invention to provide a circulating vibratory linear parts-feeder which can supply stably supply parts in the predetermined posture, to the next stage.
It is another object of this invention to provide a circulating vibratory linear parts-feeder which is widely applicable, and low cost.
In accordance with an aspect of this invention, in a circulating vibratory linear parts feeder includes: a main trough for transporting parts in one direction; and a return trough for transporting the parts in the opposite direction to the one opposition, arranged closely to the main trough, spaced a small gap from the main trough, wherein the parts are transferred from the downstream end of the return trough into the upstream end of the main trough: parts orientated in the main trough by orientating means are discharged from a discharge end to the outside and the other or remaining parts are returned from the downstream end of the main trough into the upstream end of the return trough. Thus the parts are being circulated in the main trough and return trough. The main trough comprises a transport surface for orientating the parts and an inward circulating surface which is lower than the transport surface; the return trough comprises a circulating surface and the main trough and the return trough are vibrated by drives of different frequencies, respectively. The parts are transferred from the downstream side of the return trough to the upstream end of the transport surface; the orientated parts are discharged from a discharge guide connected to the end of the main trough; and the parts being led into the inward circulating surface are transferred into the circulating surface of the return trough.
The foregoing other objects, features, and advantages of the present invention will be more readily understand upon consideration of the following detailed description of the preferred embodiments of the invention, taken in conjunction with the accompanying drawings.